Size of roof gutters.
Municipal Code of Chicago § 18-29-1106.6
in effect18-29-1106.6 Size of roof gutters.
The size of semicircular gutters shall be based on the maximum projected roof area in accordance with Table 18-29-1106.6.
Table 18-29-1106.3
Size of Horizontal Storm Drainage Piping
Pipe Size | 1/8 Unit Vertical in 12 Units Horizontal (1-percent slope) | 1/4 Unit Vertical in 12 Units Horizontal (2-percent slope) | 1/2 Unit Vertical in 12 Units Horizontal (4-percent slope)
Square Feet | Square Feet | Square Feet
Pipe Size | 1/8 Unit Vertical in 12 Units Horizontal (1-percent slope) | 1/4 Unit Vertical in 12 Units Horizontal (2-percent slope) | 1/2 Unit Vertical in 12 Units Horizontal (4-percent slope)
Square Feet | Square Feet | Square Feet
3 | 822 | 1,160 | 1,644
4 | 1,800 | 2,650 | 3,760
5 | 3,340 | 4,720 | 6,680
6 | 5,350 | 7,550 | 10,700
8 | 11,500 | 16,300 | 23,000
10 | 20,700 | 29,200 | 41,400
12 | 33,300 | 47,000 | 66,600
15 | 599,500 | 84,000 | 119,000
For SI: 1 inch = 25.4 mm, 1 square foot = 0.0929 m2.
(Amend Coun. J. 4-15-15, p. 106130, § 24)
Table 18-29-1106.6
Size of Semicircular Roof Gutters
Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet
1/16 Unit Vertical in 12 Units Horizontal (0.5-percent slope) | 1/8 Unit Vertical in 12 Units Horizontal (1-percent slope) | 1/4 Unit Vertical in 12 Units Horizontal (2-percent slope) | 1/2 Unit Vertical in 12 Units Horizontal (4-percent slope)
Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet | Diameter of Gutters (inches) | Square Feet
1/16 Unit Vertical in 12 Units Horizontal (0.5-percent slope) | 1/8 Unit Vertical in 12 Units Horizontal (1-percent slope) | 1/4 Unit Vertical in 12 Units Horizontal (2-percent slope) | 1/2 Unit Vertical in 12 Units Horizontal (4-percent slope)
3 | 170 | 3 | 240 | 3 | 340 | 3 | 480
4 | 360 | 4 | 510 | 4 | 720 | 4 | 1,020
5 | 625 | 5 | 880 | 5 | 1,250 | 5 | 1,770
6 | 960 | 6 | 1,360 | 6 | 1,920 | 6 | 2,770
7 | 1,380 | 7 | 1,950 | 7 | 2,760 | 7 | 3,900
8 | 1,990 | 8 | 2,800 | 8 | 3,980 | 8 | 5,600
10 | 3,600 | 10 | 5,100 | 10 | 7,200 | 10 | 10,000
For SI: 1 inch = 25.4 mm, 1 square foot = 0.929 m 2.
Source: City of Chicago, Municipal Code of Chicago (American Legal Publishing, codelibrary.amlegal.com)URL: https://codelibrary.amlegal.com/codes/chicago/latest/chicago_il/0-0-0-2692796Fetched: 10/24/2026